Line a 9-by-13-inch baking dish with foil, leaving a 2-inch overhang; coat with cooking spray. Mix 2 1/4 cups graham cracker crumbs and 1 1/2 sticks melted butter in a medium bowl; press into the pan. Drizzle evenly with one 14-ounce can sweetened condensed milk. Layer with 1/2 cup chocolate chips, 1/2 cup sweetened shredded coconut, one 7-ounce box roughly chopped Samoas and 1 cup chopped pecans. Gently press into the milk. Bake at 350˚ until golden and bubbling, about 25 minutes. Let cool completely. Cut into pieces.